Improvement in manufacturing steel



UNITED I STATES PATENT OFFICE.

IMPROVEMENT IN MANUFACTURlNG STEEL.

Specification forming part of Letters Patent No. 21,948, dated November 2, 1858.

To all whom it may concern Be it known that I, JOSEPH DIXON, of Jersey City, in the county of Hudson and State of New Jersey, have invented a new and Improved Process or Method of Manufacturing Steel; and I do hereby declare that the following is a full, clear, and exact description of the distinguishing characteristics of my invention and of the method of preparing the same.

By my improved process I make directly from pig or cast iron an article of steel which may be submitted to a rolling, hammering, or other process of a similar nature, or which may be broken up and melted in crucibles to produce cast-steel.

My invention is based upon the discovery which I have made, that the carbon which is mixed with the iron known as cast-iron or pig metal is not in chemical combination, but only mechanically mixed, and may be expelled therefrom by the agency of heat alone.

In the specification of a patent granted to me on the 9th day of April, 1850, I considered that oxide of iron or its equivalent was indispensable to deprive the cast-iron of a portion of its carbon, thereby partially reducing the oxide and leaving the cast-iron in a state of malleability, or, in other words, that a true carburet of iron was decomposed by the abstraction of a part of one of its elements viz., the carbon-which, combining with the oxygen of the oxide, passed oft in vapor. In the course of working by my patent above referred to I found that although the result, so far as the steel was concerned, was as anticipated, yet that the oxide of iron, though repeatedly used, was not deoxidized, as would have been the case on the commonly-received opinion of chemical decomposition eifected by electric affinity. So varying the process by the substitution of charcoal-powder for the oxide of iron (all things else remaining the same) I found that the cast-iron plates, when taken from the cementing-furnace, were precisely the same as if the oxide of iron had been useda result for which 1 was prepared, from having previously made the following experiment: I placed a rod of cast-iron in a cylinder of crucible-ware, filling the intervening space with pulverized charcoal, thus surrounding the iron completely on all sides with carbon. The vessel was then closed and, with its contents,

placed in a fire at a bright-red heat, and thus exposed for fourteen days, at the end of which time it was removed and the rod of iron taken out unaltered in its external appearance, but

breaking with afracture bright and crystalline, like blistered steel, and readily extending under the hammer. In repeating the experiment I have caused the iron to be surrounded with various other substances-as sand and ashesand have obtained the same results, from which experiments I was led to the conclusion that cast-iron kept for a length of time in such a state of heat that the particles might have freedom of motion would be, by the attraction of aggregation alone, brought into union, while the extraneous matter, supposed to be carbon, would be expelled from the iron. Thus I have shown the steps which led me to the discovery that good steel can be made from pig or cast iron by submitting it to no other influence than that of long-continued heat kept up to nearly the melting-point of cast-iron; and by experiment I have found that any substance which will not be destroyed by the heat to which the iron is subjected in the process will answer the purpose of a covering for the iron, or to form strata to keep the sheets of iron separate from each other while being heated, as hereinafter set forth.

My present invention relates to the practical application of the above discovery; and it consists in submitting pig or cast iron, in plates of suitable size and thickness, with interposed strata of the covering or separating material, to the heat of an oven for a sufficient length of time to allow the metallic particles to arrange themselves in such a way that the plates or bars attain all the properties of steel, and may be taken directly from the oven-and rolled or hammered, or may be otherwise similarly treated to form sheet or bar steel.

In working by my process I cast the pigiron in plates of about half an inch in thickness and of the size deemed requisite for the use to which the sheet or bar steel is to be ap plied. These plates I pile in an oven, such as is used in making blistered steel. The oven is then closed and heated to as high a degree as the pig or cast iron will bear without being in danger of melting. For an oven containing about ten tons of cast-iron I apply the heat for about ten days; but the time, to a certain extent,

must be left to the discretion of the operator, who will be able to ascertain whether the process has sufficiently progressed by taking out one of the plates and observing if the granular formation has been changed, and by hammer ing to see if it has assumed the character of steel. The length of time during which the heating process is to be continuedmust, in a great measure, depend on the thickness of the plates or bars and upon the quality of steel required', for the thicker the plates or bars the longer will be the time required, and with a given thickness of plates or bars the longer they are heated the softer will be the steel. After the above process has been continued for a sufficient length of timethe plates may be taken from the oven, and, either while still hot or after having been allowed to cool and then f reheated, may hcsuhmitted to the rolling, hammering, or other analogous process;'or th'ev may be broken up and melted in crucibles, in the same manner as in making cast-steel.

\Vhat I claim as myinvention, and desire to secure by Letters Patent, is-

The above process of making steel by heating pig or cast iron covered or stratified by any substance which will preserve a separation of the plates or pieces of iron through the process of heating, except so far as the use of oxide of iron as a separating material is covered by my patcntLabove referred to.

JOS. DIXON.

Witnesses:

J. B. CLEVELAND,

E. HAWKS. 

